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. 2009 Dec;150(12):5202–5204. doi: 10.1210/en.2009-1178

Figure 1.

Figure 1

Schematic model of insulin-induced GLP-1 release from intestinal L cells. Insulin binds to insulin receptors present on L cells to trigger the activation of Cdc42 within 10–15 min. Cdc42 expression is required for subsequent activation of Pak1 and MEK1/2 signaling cascades. Pak1 activation proceeds to induce F-actin remodeling, whereas MEK1/2 signals downstream to ERk1/2, with both pathways resulting in release of GLP-1. Insulin signaling may occur at alternate surfaces based upon reports of insulin receptor localization (25,26). Nutrient sensing through sodium-dependent glucose transporter-1 (SGLT1) and G protein-coupled receptors (GPCR) occurs as nutrients pass cell in the intestinal luminal surface (top).